Identification cards are well known, both for visual and machine inspection. In the latter case, it is relatively easy to build codes into the card, which codes may not be visually apparent, to enable the machine to verify only an authentic card, and it can readily be made extremely difficult to forge a card which will deceive the machine.
However, identification cards for visual inspection by the human eye to verify the holder can more readily be forged, because it is difficult to incorporate into the card a unique feature which, although readily apparent to the eye, is not readily reproducible.